In images derived by scanning documents with punched holes on a scanning device with a black platen cover, the punched holes on the copy pages typically appear as black holes. For a small scan job, these artifacts can be removed in a manual digital image enhancement operation on a pixel-by-pixel basis using widely available image processing software having an “erase” feature. Such a manual pixel-by-pixel based artifact removal method is generally not feasible in terms of time and cost for large, multi-page scan jobs commonly encountered in commercial, legal, academic, and other real-world environments.
Automated methods have been proposed for removal of artifacts in copies, such as punch holes, streaks, and blotches. In these techniques, the artifacts are identified using known image processing techniques and are automatically deleted from the scanned image data, with appropriate adjustment of the pixel values to blend in with the surrounding pixels as needed. However, such techniques have not been found satisfactory in terms of quality assurance and thus if implemented, may be still fairly operator intensive to avoid erroneous removal of original image information.
For production volume scanning operations, such as those for scanning and processing millions of document pages each day, it is common for many documents that are being processed to be originally bound in binders. There remains a need for an efficient method for removing the artifacts resulting from punched holes which can be performed without the need for operator input.